SO2's role in atmospheric redox reactions Steps: - Recall SO2 primarily acts as a reagent in its oxidation to SO3 or sulfate in the atmosphere, contributing to acid rain. - Check option A: NO2 to NO occurs via photolysis (NO2 + hv → NO + O) or reactions with radicals, without SO2 involvement. - Check option B: NO to NO2 happens via NO + O3 → NO2 + O2 or NO + RO2 → NO2 + RO, not requiring SO2. - Check option C: CO to CO2 proceeds via CO + OH → CO2 + H, a key sink for CO, independent of SO2. - Conclude D involves SO2 directly, as A–C do not. Why D is correct: - SO2 serves as a reagent in atmospheric oxidation (e.g., SO2 + OH → HSO3, leading to H2SO4 formation per tropospheric chemistry mechanisms). Why the others are wrong: - A: Involves photochemical reduction, no SO2 role. - B: Ozone or peroxy radical oxidation, SO2 uninvolved. - C: Hydroxyl radical reaction, unrelated to SO2. Not enough information on D's specific transformation, but it …